If you genuinely feel that the coach is shouty, negative and unfair, then ask your child if he enjoys playing for this coach, or if he would prefer to look for another team.
The rest of your points though, I’m tending to think you might be a bit over sensitive. If your son is ‘by far the best defender in the team’ then I guess I can understand why he is playing in defence! I appreciate that he may also have the ability to play further upfront, but most children his age want to be the goal scorers so competition for those places is much stronger. I’m sure your son is very much valued by the coaches if he is so good in defence.
I think after only two awards ceremonies ( a total of 6 awards?) its a bit early to think that your son will always be overlooked for an award.
If you have concerns, then perhaps have a friendly chat to the coach. But please don’t be “that” mum who thinks her son should get to pick and choose what position he plays at the expense of the other players (I’m sure you won’t be)
My DH was a children’s football coach for 8 years. He had a constant stream of parents who thought they knew better than him about tactics, player positions, training techniques, and how fantastic their child was at football. They were quick to criticise but slow to volunteer to help set up, clear away, give lifts etc, and in the end DH stopped coaching.
I guess what I’m saying is that while you do, of course, want your son to do well, coaches are volunteers and will be trying to do their best for all the kids. It’s never going to be easy to please everyone.